In gas turbine engines, hot high velocity air exits from the turbine through the core gas path. The exhaust gases may be constrained by an exhaust case section in the form of a corrugated annular case extension having lobes. Turbofan engines generally use exhaust mixers in order to increase the mixing of the high and low velocity exhaust gas flows. Turbo-shaft and turbo-prop engines may be provided with similar devices sometimes referred to as ejectors. Exhaust mixers/ejectors may experience thermal variation and/or radial deflection due to exposure to the high and low velocity flows. In addition, exhaust ejector/mixers may be prone to vibrations, which have negative consequences for the surrounding hardware. As such, it is generally desirable to increase the stiffness or rigidity of the exhaust case. Various configurations of exhaust ejector/mixers have been proposed to date in order to try to increase the stiffness or reduce deflection thereof.
Also, the aerodynamic performance of ejectors is often limited by the ability of the primary flow to entrain the secondary cooling flow. Increasing the ejector capacity of pumping secondary mass flow would also be desirable from an aerodynamic point of view.